Android学习之多线程开发总结<三>

    private void connect() {  
        MyTask task = new MyTask(this);  
        task.execute(url.getText().toString());  
    }    
    
    private class MyTask extends AsyncTask<String, Integer, String> {  
        private Context ctx;
        private ProgressDialog pdialog;
        public MyTask(Context ctx){
            super();
            this.ctx = ctx;
            //创建ProgressDialog
            pdialog = new ProgressDialog(ctx, 0);     
            pdialog.setButton("cancel", new DialogInterface.OnClickListener() {  
                public void onClick(DialogInterface dialog, int i) {  
                    //dialog.cancel();  
                }  
            });  
            pdialog.setOnCancelListener(new DialogInterface.OnCancelListener() {  
                public void onCancel(DialogInterface dialog) {  
                    finish();  
                }  
            });  
            pdialog.setCancelable(true);  
            pdialog.setMax(100);  
            pdialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);  
            pdialog.show();  
        }
    
        //onPreExecute方法用于在执行后台任务前做一些UI操作  
        @Override  
        protected void onPreExecute() {  
            Log.i(TAG, "onPreExecute() called");  
            //textView.setText("loading...");  
        }  
          
        //doInBackground方法内部执行后台任务,不可在此方法内修改UI  
        @Override  
        protected String doInBackground(String... params) {  
            Log.i(TAG, "doInBackground(Params... params) called");  
            try {  
                HttpClient client = new DefaultHttpClient();  
                HttpGet get = new HttpGet(params[0]);  
                HttpResponse response = client.execute(get);  
                if (response.getStatusLine().getStatusCode() == HttpStatus.SC_OK) {  
                    HttpEntity entity = response.getEntity();  
                    InputStream is = entity.getContent();  
                    long total = entity.getContentLength();  
                    ByteArrayOutputStream baos = new ByteArrayOutputStream();  
                    byte[] buf = new byte[1024];  
                    int count = 0;  
                    int length = -1;  
                    while ((length = is.read(buf)) != -1) {  
                        baos.write(buf, 0, length);  
                        count += length;  
                        //调用publishProgress公布进度,最后onProgressUpdate方法将被执行  
                        publishProgress((int) ((count / (float) total) * 100));  
                        //为了演示进度,休眠500毫秒  
                        Thread.sleep(500);  
                    }  
                    return new String(baos.toByteArray(), "gb2312");  
                }  
            } catch (Exception e) {  
                Log.e(TAG, e.getMessage());  
            }  
            return null;  
        }  
          
        //onProgressUpdate方法用于更新进度信息  
        @Override  
        protected void onProgressUpdate(Integer... values) {  
            Log.i(TAG, "onProgressUpdate(Progress... values) called");  
            //pdialog.setProgress(values[0]);
            //textView.setText("loading..." + values[0] + "%");  
        }  
          
        //onPostExecute方法用于在执行完后台任务后更新UI,显示结果  
        @Override  
        protected void onPostExecute(String result) {  
            Log.i(TAG, "onPostExecute(Result result) called");  
            //pdialog.dismiss();  
            //textView.setText(result);   
        }  
          
        //onCancelled方法用于在取消执行中的任务时更改UI  
        @Override  
        protected void onCancelled() {  
            super.onCancelled();  
            Log.i(TAG, "onCancelled() called");  
            //textView.setText("cancelled");  
        }  
    }